In this article, the influence of fumed silica nanofiller on the structure and properties of segmented polyurethane elastomer (PUR) was investigated. In order to investigate the interactions at the filler-matrix interface, nonmodified and commercially modified fillers (with methacrylsilane and octylsilane) were used. The PUR composites with 1.0, 2.0, 4.0, 6.0, and 9.0 vol % of all fillers were prepared by solution casting method. Surface free energy of the fillers and polymer matrix was determined using contact angle measurements with different testing liquids. Change in morphology was analyzed using optical polarization microscopy and distribution of the filler in polymer matrix using scanning electron microscopy. The influences of silica fillers on mechanical and thermal properties of PUR were investigated. Results showed that sur-face treatment of silica filler with methacrylsilane and octylsilane reduces the agglomeration of particles that improves dispersion at microlevel. Addition of all fillers disrupts spherulite morphology and decreases crystallinity of the PUR matrix. Nonmodified silica nanofiller has the least pronounced influence on spherulite morphology and the lowest influence on polyurethane crystallinity and thus the best mechanical properties. Surface modification of silica with octylsilane has less influence on polyurethane crystallinity and on decreasing of mechanical properties than modification with methacrylsilane. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125: E181-E190, 2012

In this study influence of monomer ratio, butyl acrylate (BA), and methyl methacrylate (MMA) as well as silica nanofiller morphology (pyrogenic and colloidal) and concentration on the emulsion particle size distribution and properties of polyacrylate film (PA) synthesized by in situ emulsion polymerization were investigated. The ratios of the monomers BA/MMA were 100/0, 70/30, 50/50, 30/70, 0/100 and the filler concentration 0–10.0 mass%. PA nanocomposite films were characterized by using thermogravimetric analysis, differential scanning calorimetry, and tensile test. Research has shown that monomer ratio has significant influence on glass transition temperature (Tg). The addition of both types of silica filler, pyrogenic and colloidal, has no effect on Tg. Thermogravimetric analysis showed that systems with higher BA fraction have better thermal stability than systems with higher MMA fraction. Addition of the both type of silica nanofiller enhanced thermal stability of PAs, however, systems with colloidal silica are more stable. Pyrogenic silica and higher amounts of colloidal silica nanofiller increased PA emulsion particle size up to several micrometers. Addition of higher amounts of colloidal silica improved mechanical properties compared to the neat PA matrix. POLYM. ENG. SCI., 53:2292–2298, 2013. © 2013 Society of Plastics Engineers

In this article, isothermal crystallization kinetic of the linear hydroxyl polyester urethane (PUR), as well as influence of amorphous silica nanofiller, was investigated. With the aim to investigate the influence of filler surface modification on the crystallization process of polyurethane matrix, nonmodified silica, as well as silica modified with methacrylsilane and octylsilane, were used as fillers for PUR composite preparation. The crystallization kinetics depending on temperature of the isothermal crystallization and volume fraction of filler by using differential scanning calorimetry (DSC) were investigated. The measurements at temperatures 7, 12, and 17°C for PUR and composites with 0.5, 1, 2, and 4 vol % of filler were done. Kinetic parameters of the isothermal crystallization n and K were determined according to Avrami model. Melting of the isothermally crystallized samples was also investigated. Results of the research indicate that by increasing the isothermal crystallization temperature, the crystallization rate of the PUR soft phase decreases and that the perfection of the crystallites is improved. By addition of all fillers up to ≈1 vol %, the crystallization rate increases; however, addition of a higher amount of the filler significantly decreases the crystallization rate. It was found that surface modification can significantly affect crystallization rate and that the nucleation efficiency of silica increases in the following order: methacrylsilane‐modified silica < nonmodified silica < octylsilane‐modified silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013